1. Field of the Invention
The present invention relates to a method for handling sheet stacks.
Furthermore, the invention relates to an apparatus for handling sheet stacks.
2. Description of Background Art
Known in the art are handling systems for sheet stacks in which the storage of the sheet stacks is implemented using stacker trucks. However, the use of stacker trucks requires plenty of space between the piled sheet stacks and wide truck aisles. Moreover, storage handling of sheet stacks using stacker trucks is difficult to automate.
Also known are systems using transfer beds for the transport of sheet stacks to the storage. The sheets are stacked in high piles which are then transferred to the storage by means of a transfer bed. The transfer beds travel in the storage under sheet stacks piled on supports such as concrete pillars. Such systems are hampered by, the limitation that sheet stacks piled in the storage can be picked from the storage only in a certain order, which prevents random picking of the sheet stacks, e.g., directly from the center of the sheet stack storage. Moreover, the storage requires complicated and expensive foundations.
Further known is a storage system in which the sheet stacks are stored on a pallet with a planar top surface. After stacking, a lift carrier is used to transfer the sheet stack piled on the pallet to the storage. In practice the handling of such sheet stack pallets has proven complicated. They require purpose-designed handling equipment to be used on the processing lines of the sheets. The pallet must be transferred into a stacking station, where the sheets are piled one by one into stacks onto the pallet. When unloading the sheets from such a pallet, the sheets must again be removed one by one from atop the pallet for use on a processing line. Having a conventional construction, the pallets require an operating environment comprising dedicated handling equipment, a pallet storage from which they are fed to the stacking device of the processing line of the sheets, and additionally, equipment for collection and transfer of the pallets back to the storage. Such arrangements are often extremely complicated and require different kinds of equipment for handling the pallets.